Method of forming a non-torque curled yarn



Jan. 2, 1968 M. H. COMER ETAL METHOD OF FORMING A NON-TORQUE CURLED YARN 2 Sheets-$heet 1 Filed Oct. 20, 1965 v I ATTORNEYS M T mm mam fiw QB a w WMM MW Jan.2, 1968 COMER ETAL r 3,360,838

Filed Oct. 20, 196i v 2 Sheets-Sheet 2 MAQWN H. COME-12 and WILUAM \MBuslci ATTORNEY S INVENTORSI United States Patent 3,360,838 METHOD OF FORMING A NON-TORQUE CURLED YARN Marvin H. Corner and William W. Busick, Burlington,

N.C., assignors to Alamance Industries, Inc., Burlington, N.C., a corporation of North Carolina Filed Oct. 20, 1965, Ser. No. 498,905 5 Claims. (Cl. 28-72) ABSTRACT OF THE DISCLOSURE Non-torque characteristics and internal torsional stresses are imparted to thermoplastic yarn producing periodically reversing curls therein of sufficient magnitude that the yarn can be satisfactorily knit to form ladies sheer stretchable stockings by passing the yarn through a heating zone where it is softened, and around a support to form a half-hitch type knot configuration so that the running yarn passes over and rubs against itself at least two times when in a heat softened condition. The yarn may be knit into stockings or the like and subjected to heat to develop the latent torsional stresses to impart stretchability thereto to the fabric.

This invention relates generally to a method of initially processing a normally non-stretchable thermoplastic yarn and forming a stretchable, non-torque yarn having relatively large periodically reversing curls therein, and more particularly to a method of processing a yarn of this type wherein internal torsional stresses are also initially imparted to the yarn which may be released by the subsequent application of heat to drastically reduce the size of the curls so that they form very small periodically reversing closely spaced substantially uniform spring-like helical coils or curls along the length of the yarn. This yarn is particularly adapted for use in the knitting of stretchable articles of clothing, such as ladies sheer hoisery and the like, wherein the initially processed yarn is knit and then the subsequent application of heat is applied to the fabric to further develop the initially formed curls.

There are several known methods of processing a normally non-stretchable thermoplastic yarn, such as nylon, to initially impart internal torsional stresses or torque to the yarn so that crim-ps, curls or coils may be developed in the yarn. For example, nylon yarns have been drawn over a heated blade to provide a curly effect to the yarn and to impart internal torsional stresses which may be further developed. While this type of yarn has balanced torque, it is difficult to maintain a uniform size because of variations in the tension of the yarn and because the blade cannot be maintained at a constant degree of sharpness.

It has been suggested that a potentially curly yarn may also be formed by passing a thermoplastic yarn around a heated roller and then across a single length of itself in such a manner that the portion of the yarn to be curled travels over a preceding portion of itself at an angle of about 170 (see Australian Patent No. 227,591, published Nov. 13. 1958, and the corresponding British Patent No. 839,393). However, yarn processed in accordance with this method does not produce curls which are small enough to form satisfactory fine gauge stretchable knitted fabrics, such as ladies hoisery and the like.

US. Patent No. 3,178,795 to William P. Warthen discloses wrapping a yarn completely around a transversely moving preceding segment of itself for a full turn of 360. In order that the wrapped yarn will not ride, bind and break as it passes around its preceding segment, the tension on the wrapped portion must be maintained at a lesser amount than the tension on the transversely mov- 3,350,838 Patented Jan. 2, 1968 ing preceding segment. This process is relatively slow and expensive.

The Earl H. Biggers US. Patent No. 3,035,396 also discloses looping a yarn around itself, but this produces a torque yarn which does not produce a usable fabric when knit by itself but which must be alternately knit with yarn of Opposite torque, in order to balance the overall torque of the fabric.

With the foregoing in mind, it is a main object of the present invention to provide a method of forming a stretchable, non-torque, curled yarn which is economically carried out at a rapid production rate and in a relatively simple manner.

It is a more specific object of the present invention to provide a method of initially processing a yarn of the type described which may be easily knit into ladies sheer hosiery in a single-feed manner without requiring any changes or special procedures during the knitting and finishing of the hosiery knit therefrom and wherein the finished hosiery has uniform stretch and a bulky, somewhat pebbled or creped appearance.

The foregoing objects as well as other objects are accomplished by passing the yarn through a heating zone to soften the same and immediately forming a looped portion in the softened yarn and continuously adding and withdrawing yarn from the looped portion while passing the yarn withdrawn from the looped portion around a support and then through the looped portion so that the running yarn assumes a half hitch type knot configuration around and adjacent the support.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which- FIGURE 1 is a somewhat schematic vertical sectional view through one station of an apparatus which is suitable for carrying out the initial processing of the yarn in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary isometric view of a portion of FIGURE 1, looking inwardly along the arrow 2 and illustrating the manner in which the half hitch type knit configuration is formed around the support immediately after the yarn passes out of the groove in the heater block;

FIGURE 3 is an enlarged vertical sectional view through the support and illustrating the manner in which the yarn is drawn across itself in the half hitch type knot configuration;

FIGURE 4 is a greatly enlarged elevational view of the running yarn and illustrating the half hitch type knot in greater detail;

FIGURE 5 is a greatly enlarged fragmentary view of the initially processed yarn, illustrating the manner in which relatively large periodically reversing curls or coils are formed in the yarn when it is in relaxed condition;

FIGURE 6 is a view of the yarn shown in FIGURE 5 after the same has been subjected to boiling water and illustrating the manner in which the potential curl or coils of the yarn is fully developed so that the size of the curls is decreased and the number of curls per inch is greatly increased;

FIGURE 7 is a greatly enlarged fragmentary portion of a fine gauge hosiery fabric knit of the partially developed yarn shown in FIGURE 5; and

FIGURE 8 is a view similar to FIGURE 7 but illustrating the appearance of the relaxed fabric after it is subjected to a finishing operation to more fully develop the curls in the yarn.

Generally, the present invention is particularly concerned with thermoplastic yarns of the type that are normally utilized in the knitting of fine gauge ladies sheer w hosiery and which fall within the range of from about 10 denier to 40 denier, both monofilarnent and multifilament. However, it is to be understood that the present method may also be utilized with other types and sizes of thermoplastic yarns which are knit or woven to form stretchable articles of clothing.

As has been pointed out, the present method generally includes heating the yarn and then forming a half hitch type knot configuration around a support so that the running yarn is rubbed against itself several times and passes over itself. When relaxed, the yarn will then form periodically reversing, relatively large curls throughout the length thereof and internal torsional stresses are imparted to the yarn. These internal torsional stresses may be subsequently released by the application of heat, such as by subjecting the relaxed yarn to boiling water, so that the initially formed curls are reduced to less than onefourth their original size. However, the potentially curly yarn is normally knit in the leg portion of hosiery after the initial process so that the stitch loops are only slightly distorted, as shown in FIGURE 7, as the yarn is relaxed and tries to form relatively large curls therein, as shown in FIGURE 5. Then the hosiery is subjected to a heating treatment so that the stitch loops become more distorted, as shown in FIGURE 8, as the yarn attempts toforrn the small coils, as shown in ETGURE 6.

However, due to the knit construction of the hosiery fabric, the curl in the yarn cannot be developed to the position shown in FlG. and the stitch loops are only slightly distorted. When the hosiery fabric is subjected to the heat treatment to further develop the curls, they cannot be fully developed to the position shown in FIG- URE 6. However, the stitch loops become more distorted, as show in FIGURE 8, and some of the stitch loops distort toward one face of the fabric while others distort and bow or bend toward opposite faces of the fabric so that the relaxed fabric has a somewhat pebbled, creped and bulky appearance. When the hose is worn on the legs, the fabric is stretched so that the yarn substantially straightens out and the stitches assume their normal shape thereby presenting a sheer appearance when worn on the leg. When the hose is removed from the leg, the stitch loops return to their distorted position.

Referring particularly to the drawings, a preferred type of processing apparatus is schematically shown in FIG- URE 1. The apparatus preferably includes a plurality of yarn processing stations, although only one station is shown in FIGURE 1.

The thermoplastic yarn Y, such as nylon, is continuously withdrawn from a yarn supply pirn it! which is preferably of the type on which the yarn is supplied by the manufacturer. The yarn Y then passes through yarn guide eyes 11, a disk type tension device it and through the groove 13 of a heater plate 14. As is shown in FIG- URE 2, the yarn is preferably passed through the groove 13 so that it does not engage the sides or bottom.

Immediately after the yarn leaves the heater plate 14, it is formed into a half hitch type knot configuration, broadly indicated at K in FIGURES 1 and 2. The half hitch type knot K is formed around a ceramic support in the form of a guide pulley 2% which is suitably supported on the lower end of a bracket 21, fixed at its upper end on the lower portion of the heater block 1 The portion of the pulley 2b which is contacted by the running yarn preferably has a small diameter, on the order of about m; of an inch.

The yarn Y then passes over a guide pulley 24 and downwardly around a pair of yarn feed rolls 25 which is suitably driven at the desired speed by a gear The yarn then passes through a pair of spaced apart guide eyes 27, 28 and in engagement with a yarn lubricating applicator roll 3d. Suitable lubricant is supplied to the roll by means of a supply trough The yarn Y is then wound onto a take-up bobbin 32, preferably by means of a vertically moving traveler ring 33. The yarn is preferably wound on the take-up bobbin 32 in the same manner as it is usua ly wound on the supply pirn Eli) so that it may be directly Jithdrau and knit from the bobbin 32. A drive belt imparts rotation to the take-up bobbin 32.

in the apparatus shown in FIGURE 1, the yarn is being pulled from the supply pirn ill by means of the feed rolls 25 and the tension on the yarn as it passes through the heater l t and the half hitch knot may be controlled by adjusting the disk tension device 12. However, the tension on the yarn may also be controlled by passing it around a pair of upper feed rolls, indicated in dotted lines at 3:5 in HGURE l. The upper feed rolls 3 5 are driven at the desired speed by gear as. The speeds of the upper feed rolls 35 and the lower feed rolls 25 may be varied to thereby vary the amount of tension on the yarn Y as it passes through the heater block i l and the half hitch knot K.

Referring particularly to FIGURES 3 and 4, will be noted that the running yarn Y is first formed into a looped portion c immediately below the heater id and the yarn is continuously added to and withdrawn from the looped portion 0, The looped portion c of the running yarn encompasses less than 360 and, as best shown in FIGURE 4, the looped portion encompasses approximately 270 from the point at which the yarn enters around to the point at which it leaves. The yarn crosses and rubs against itself at right angles as it enters and leaves the looped portion c. The rubbing action of the yarn against itself imparts a twisting rotational movement to the yarn and also imparts internal torsional stresses thereto. Leaving the looped portion 0 the yarn passes around the support 2% to form the bight i) of the half hitch knot K. As the yarn passes through the bight b and in engagement with the surface of the support 2%, the twisting of the yarn is stopped.

The yarn Y then moves upwardly from the support 26 and passes through the looped portion 0 as it moves to the guide pulley 26. As the yarn passes through the looped portion 0, it is bent almost and rubbingly engages the yarn of the looped portion 0. The angle between the yarn entering and leaving the half hitch knot K is approximately 90.

Thus, the yarn running through the half hitch type knot K passes over itself and rubs against itself at least two times while it is still in a heat-softened condition so that opposing twist forces and internal torsional stresses are imparted to the yarn. This initially processed yarn forms relatively large periodically reversing curls along its length when the yarn is relaxed. This initial curl can be reduced in size and more fully developed as the internal torsional stresses are released by a subsequent heat treatment.

The yarn is wound onto the tal eup bobbin 32 under tension and is in substantially straight condition Without any visible curl or coil therein. When the yarn is withdrawn from the bobbin 3?; and allowed to relax at room temperature for a few minutes, it assumes the curled configuration, substantially as shown in FIGURE 5, and the curls periodically reverse their helical direction of rotation at irregular intervals, as indicated at the loops 37. The curls may be more fully developed, as shown in F1- URE 6, by winding the yarn into relaxed skeins and placing the skeins in boiling water. However, it is preferred that the initially processed yarn be knit directly from the take-up bobbin 32 and maintained in substantially straight condition during the knitting operation, In the unfinished knit fabric, the yarn attempts to assume the curled position shown in FIGURE 5 so that the stitches of the knit fabric are slightly distorted, as shown in FIGURE 7. Then the hit fabric is subjected to a heat treatment, such as hot water, to release the internal torsional stresses in the yarn so that it attempts to assume the curled condition shown in FIGURE 6. The knit construction prevents the full development of the curls, however, the stitch loops become much more distorted, as shown in FIGURE 8, thereby imparting a substantial degree of stretchability to the fabric.

In order to provide a more specific description of the invention, the following non-limiting example may be followed to form ladies stretchable sheer hosiery.

A raw denier monofilament nylon yarn, as received from the manufacturer, is processed on the apparatus shown in FIGURE 1 at a rate of 160 yards per minute while the heater block 14 is maintained at a temperature of about 400 F. When a length of this initially processed yarn is allowed to relax at room temperature for about five minutes, the curls therein measure about of an inch in diameter. When this same length of yarn is heated in relaxed condition the curls reduce to about one-fourth their original size or to about & of an inch in diameter.

The initially processed yarn, while still on the take-up bobbin or pirn 32, is fed to the knitting machine and utilized in knitting at least the leg portion of the ladies hose. If desired, the welt, heel and toe of the hose may be knit of some other type of yarn. Since the overall torque of the yarn is balanced, the leg of the hose may be knit in a single-feed manner, if desired.

The internal torsional stresses of the yarn may be released during the usual finishing operations to which the hose is subjected and which include applying heat to the hose, such as preboarding, dyeing, scouring and final boarding. However, it is preferred that the hose first be subjected to boiling water (212 F.) with slight agitation to release the torsional stresses in the yarn before proceeding with the normal finishing process.

Other sizes and types of yarns may also be processed in accordance with the present method. The yarn may be either monofilament or multifilament. For example, multifilament /7 denier nylon and 40/ 13 denier nylon yarns have produced very satisfactory results when processed in accordance with this invention.

The process heretofore described may be termed a single process, that is, the yarn is run through the apparatus shown in FIGURE 1 only one time. However, the yarn may be subjected to a double process in which the same yarn is run two times through the apparatus shown in FIG- URE 1. It has been found to be preferable that a slightly lower temperature be used when the yarn is processed two times. A slightly smaller curl has been produced by processing the yarn two times and the smaller curl is somewhat easier to develop.

The half hitch knot configuration K is formed about a support which is shown in the drawings as being in the form of a guide pulley 20; however, it has also been found that it may be formed about an alsimag pin of about .003 of an inch in diameter. Also, the half hitch knot K may be formed in a different manner than that shown in the drawings. For example, it has been found that the looped portion 0 (FIGURE 4) may be formed in the reverse direction from that shown.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

We claim:

1. A method of processing a thermoplastic yarn to impart non-torque characteristics and internal torsional stresses thereto to produce periodically reversing curls therein comprising the steps of (a) passing the yarn through a heating zone to soften the same,

(b) forming a loop portion in the softened yarn and continuously adding and withdrawing yarn from the looped portion while passing the yarn withdrawn from the looped portion around a support and then through the looped portion so that the running yarn assumes a half-hitch type knot configuration, the half-hitch type knot causing the running yarn to pass over and rub against itself at least two times while in a heat softened condition so that opposing twist forces and internal torsional stresses are imparted thereto; the angle between the yarn entering and leaving the half-hitch knot being approximately 90, and

(c) collecting the processed yarn.

2. A method according to claim 1 wherein the thermoplastic yarn has a denier size of from about 10 to about 40.

3. A method according to claim 2 wherein the thermoplastic yarn is nylon.

4. A method of processing a thermoplastic yarn to initially produce relatively large periodically reversing curls and to impart non-torque characteristics and internal torsional stresses therein which may be released to reduce the size of the curls and increase their frequency to provide small closely spaced, substantially uniform, spring-like helical coils therein, the rotational direction of said coils periodically reversing along the length of the yarn to balance the overall torque of the yarn, said method comprising the steps of (a) passing the yarn through a heating zone to soften the same,

(b) forming a loop portion in the softened yarn and continuously adding and withdrawing yarn from the looped portion while passing the yarn withdrawn from the looped portion around a support and then through the looped portion so that the running yarn assumes a half-hitch type knot configuration, the half-hitch type knot causing the running yarn to pass over and rub against itself at least two times while in a heat softened condition so that opposing twist forces and internal torsional stresses are imparted thereto; the angle between the yarn entering and leaving the half-hitch knot being approximately 90,

(c) collecting the processed yarn,

(d) at least partially relaxing the processed yarn, and

(e) heating the partially relaxed yarn to release the internal torsional stresses and develop the small spring-like helical coils therein.

5. A method of forming stretchable hosiery comprising the steps of (a) processing a thermoplastic yarn to produce nontorque characteristics and a potential curl therein y (1) passing the yarn through a heating zone to soften the same,

(2) forming a looped portion in the softened yarn and continuously adding and withdrawing yarn from the looped portion while passing the yarn withdrawn from the looped portion around a support and then through the looped portion so that the running yarn assumes a half-hitch type knot configuration, the half-hitch type knot causing the running yarn to pass over and rub against itself at least two times while in a heat softened condition so that opposing twist forces and internal torsional stresses are imparted thereto; the angle between the yarn entering and leaving the half-hitch knot being approximately 90,

(3) collecting the processed yarn,

(b) knitting at least the leg of the hose of the processed yarn, and

(c) heating the hose in at least partially relaxed condition to develop the potential curl in the yarn and cause the stitch loops to distort and provide stretchability to the leg of the hose.

References Cited UNITED STATES PATENTS 3,035,396 5/1962 Biggers 28-72 X 3,148,520 9/1964 Biggers 28-72 X 3,178,795 4/ 1965 Warthen 28-72 FOREIGN PATENTS 227,591 4/1960 Australia.

ROBERT R. MACKEY, Primary Examiner. 

